Transformer



Patented June 18, 1929.

UNITED STATES PATENT OFFICE JOHAN ROMP AND WIEBOLD FRANS BRANDSMA, OFF-INDHOVEN, NETHERLANDS, AS- SIGN ORS TO N. V. PHILIPSGLOEILAMPENFABRIEKEN, A LIMITED LIABILITY COM- PANY OF THE NETHERLANDS.

TRANSFORMER.

No Drawing. Application filed February 15, 1928, Serial No. 254,603, andin the Netherlands March I This invention relates to transformers andmore particularly small transformers, for example, those which are usedin wireless telephony and telegraphy.

As a rule the windings of such transformers are composed of wires ofcopper. A disadvantage of copper is that its tensile strength is notgreat and its resistance to corrosion is insufficient.

The transformer according to the invention is characterized in that atleast one of the windings is composed of wire which consists of an alloyof copper and silver. The tensile strength of such an alloy is greaterthan that of copper so that it is possible to draw the alloy down intowires having a smaller diameter than is possible in the case of copper.In addition the resistance to corrosion of the alloy is materially moresatisfactory than that of copper.

Satisfactory results are obtained by the use of an alloy containing atleast 94% of silver. As a result of the high content of silver there isno free copper left in the alloy so that practically no oxidationoccurs. In addition the tensile'strength is materially increased. As thealloy moreover has only a very low ohmic resistance it serves admirablyas material for the wire of the primary of low-frequency transformersused in wireless telephony and telegraphy.

The alloy may have added to it small quantities of nickel with theresult that the probability of oxidation is further decreased so that inpractice the wire proves still more resistant to external influences. Asit has been established by experiments nobody has yet succeeded informing alloys of nickel and silver so that the manufacture of silvernickel .wire is at present unknown. In the case of the alloy embodyingthe invention and containing at least 94% of silver it is possible toadd nickel and thus to obtain an alloy capable of being drawn into wireof superior quality. This wire can be drawn out into a very fine wire sothat it is possible for transformers wound with that wire to have verysmall dimensions. The wire being not or hardly liable to oxidation thesetransformers also have a very long life.

For transformer windings enamelled copper wire is mostly used. Itstensile strength is 30 kg/mm. The tensile strength is consequentlymaterially lowered by the enamelling operation. According to theinvention enamelled wire having a core consisting of an alloy of copperand silver may be used for transformer windings. The advantage of thisalloy over copper consists in that the tensile strength is not loweredby the enamelling operation.

What we claim is:

1. A transformer for radio or like parposes, one of the windings thereofbeing composed of wire, which consists of an alloy of copper and silver.

2. A transformer for radio or like purposes, one of the windings thereofbeing composed of an alloy containing copper and at least 94% of silver.

3. A transformer according'to claim 2, in which the alloy includes smallquantities of nickel.

4. A transformer for radio or like purposes, in which one of thewindings is of enamelled wire the core of which wire consists of analloy of cop er and silver.

In testimony whereo we afiix our signatures, at the city of Eindhoven,this 25th January, 1928.

J OHAN ROMP. WIEBOLD FRANS BRANDSMA.

